Method of stamping laminations

ABSTRACT

The present invention is an improvement upon an earlier invention relating to a scrapless method of stamping E laminations from an endless strip of metal. The pattern in this particular method involves stamping small circular and semicircular apertures in the metal strip, respectively, at the regions where right angle die punches cluster and terminate at the edge of the metal strip so that there is no metal in the strip from which spurs may develop. Also, this differs from the previous inventions whereby the inner E&#39;&#39;s were stamped out first, leaving the outer edges of the strip to be cut off as small and large E laminations. In this invention the patent changes as follows: Two E&#39;&#39;s are removed from the outer edges of the strip, one small and one large, leaving the center of the strip as a skeleton to subsequently to chopped off as small and large E&#39;&#39;s.

United States Patent 91 Hirai et al.

[ METHOD OF STAMPING LAMINATIONS Inventors: Robert K. I-Iirai, LaMiranda; John H. Boomer; Edward R. Small, both of Fullerton, all of Calif.

DISCHARGED TO FORM LAYERS (STACK) OF NOTCHED INNER 5'8 11] 3,715,943 Feb. 13, 1973 Primary Exdminer.lames M. Meister Attorney-Vincent G. Gioia and Robert F. Dropkin 5 7 ABSTRACT The present invention is an improvement upon an earlier invention relating to a scrapless method of stamping E laminations from an endless strip of metal. The pattern in this particular method involves stamping small circular and semicircular apertures in the metal strip, respectively, at the regions where right angle die punches cluster and terminate at the edge of the metal strip so that there is no metal in the strip from which spurs may develop.

Also, this differs from the previous inventions whereby the inner Es were stamped out first, leaving the outer edges of the strip to be cut off as small and large E laminations. In this invention the patent changes as follows: Two Es are removed from the outer edges of the strip, one small and one large, leaving the center of the strip as a skeleton to subsequently to chopped off as small and large Es.

1 Claim, 5 Drawing Figures mscmnaso r0 manure-Rs (suck/0F IVOTCHED OUTER ES DISCHARGED 70 FORM LAYERS (srAc/r) 0F NOTCHED OUTER E'S l/VVE/VTORS.

PATENTED FEB 13 I975 DISCHARGED r0 FORM LAYERS (STACK) 0F NOTCHED INNER E'S 8 LN M 0 AR M n M 0 r 5H 0 0 aka 0 DNHAA 43 H W00\ 0 W m METHOD OF STAMPING LAMINATIONS .This invention relates to a generally scrapless method of stamping E laminations from an endless metal strip. The invention to be hereinafter disclosed is an improvement upon, and overcomes certain disadvantages-encountered with the practice of the invention embodied in, US. Pat. No. 3,491,437, issued Jan. 27, 1970, to Edward R. Small, assigned to the same assignee as the present application; A stamping pattern is disclosed wherein two rows of interlocked small Es on one side of an imaginary dividing line along a strip of metal is transversely aligned, with two interlocked rows of large Es on the other side of said imaginary dividing line. All Es have end legs of equal width extending laterally from similarly dimensioned bases. The center leg for the Es is twice the width of the end legs. The lengths of the legs of the large E's are the same and are longer than the lengths of the legs of the small Es which are also the same. As more fully pointed out in US. Pat. No. 3,456,535, the stamping pattern makes it possible to use the original strip metal without any significant amount of scrap.

Scrapless stamping of lamination metal is particularly important. in the case of the rather expensive nickel-bearing alloys used in such laminations. As an example, alloys containing about 80 percent of nickel are frequently used for laminations. Such alloys at the present time run about $4.00 a pound. It has generally been the practice for the industry to tolerate as much as 50 percent scrap loss. The recovery in the way of resale value of said scrap is generally about percent of the original metal price. The result is that in practice, stamped laminations of such nickel alloys may represent a cost'of substantially $7.00 per pound. The tonnage involved in such lamination manufacture is substantial. I

The stamping pattern disclosed and claimed in the aforementioned Small patent is highly efficient and the application of the invention to production has resulted in great savings. However, in connection with the preferred stamping pattern disclosed therein spurs may still occur at points .in the stamping pattern, where shear lines terminate at the edge of the strip rnetal. These points occur, in the particular stamping pattern referred to, along a plurality of imaginary transverse lines marking the length of the Es bordering the outer portions of the strip metal. In addition, it has since been found that the stamping pattern referred to, presents a danger of creating material hang up such as may result in die damage due to an unstable strip skeleton sub- Y sequent to separation of the inner E's from the metal strip.

This invention makes it impossible for spurs to occur at the outside corners of both the inner and outer E's while simultaneously producing a stronger and more stable skeleton after removal of the outer Es whereby a smoother material flow results with less danger of material hang up resulting in die damage. The applicat'ionof the present invention results in the creation of some strip metal scrap in an amount which is so small (less than 2 percent) that for all practical purposes, scrapless production of laminations is still true.

Some of the E lamina produced by prior scrapless methods have spurs which interfere with the. assembly spurs cause a gap between adjacent butted Es, which gap known as coplanar such as in the case of 0.006 and 0.014 in. thick strip stock, may run in excess of the 0.001 in. maximum gap permissable. In addition, instability of the strip stock, subsequent to the punching of some of the Es, as in prior art methods, results in an unstable strip skeleton which during its travel through the die rails and alignment by pilot members hangs up which oftentimes results -in die damage.

The invention contemplates pre-punching small apertures or semi-circular notches through the endless metal strip. The small generally circular apertures are punched along the imaginary longitudinal dividing line in the stamping pattern, at intervals corresponding to the length of an E base, at the intersection of the transverse lines of metal shear and the imaginary dividing line. The generally semi-circular notches or semi-circular apertures are punched along the outer edges of the strip at imaginary transverse lines at intervals corresponding to the length of an E base with the base of the semi-circular notch being coincident with the outer edge of the metal strip. This removes the strip metal at regions which may be sources of spurs at the outer corners of all the Es. The removal of the-semi-circular portions has been found to produce a strongerand more stable skeleton after removal of the outer Es and also remove the camber condition from slitting, which would otherwise be evident.

For an understanding of the invention reference will now be made to the drawings wherein FIG. 1 is a plan view of a stack of E laminations from the outer rows of Es, the outer corners of the'layers, each consisting of a smalland large E, being notched.

FIG. 2 shows a plan view of a stack of E laminations, derived from the inner rows of Es, the outer corners of the layers, each consisting of a small and large E, being notched.

FIG. 3 is an enlarged plan view of a length of lamination metal illustrating a stamping pattern in connection with which the invention is useful.

FIG. 4 is a plan view of a multi-station punching procedure utilizing the stamping'patternillustrated in FIG. 3, this view also illustrating selective discharge paths of the outer and inner E rows.

FIG. 5 shows a skeleton" of a portion of the endless metal strip subsequent to the removal of some of the outer E's.

Metal strip 10 is endless and is of lamination metal whose overall width is designated as 11. Extending longitudinally of strip vl0 is imaginary dividing line 12 between inner row 14 of successive small E's and inner row 15 of successive large E's, these two inner rows being disposed in back to back relation on opposite sides of imaginary dividing line 12. Interlocked with inner row 14 of small Es is outer row 16 of successive small Es, the outer edge 18 of this row constituting the outer edge of the strip. Extending transversely of strip 10 are imaginary lines 23a and 23b which define the I length of the Es.

of acceptable transformer or choke laminations. The

It is understood that the showing of FIG. 3 is illustrative of a stamping pattern. At spaced intervals along imaginary dividing line 12, and meeting the same at right angles thereto, are transverse shear lines 21a and 21b. Shear line 21a extends across inner row 14 of small Es while shear line 21b extends across inner row of large Es. While shear lines 21a and 211) should form one continuous line extending across imaginary dividing line 12 at points 22, this does not actually occurin the idealized geometry of the stamping pattern. The actual shearing of the metal about point 22 will occur at different times. Transverse shear lines 210 and 2111 do not form one continuous shear line with real dies (although in transverse alignment) and do not intersect imaginary dividing line 12. This is due to the lack of geometrical precision of a die cutting edge.

Dividing Iine12 is imaginary only as part of a stamping pattern considered with respect to the endless strip prior to stamping or punching. Actually the separation between the back to back Es in inner rows 14 and 15 does occur along dividing line 12 although it is understood that separation along line 12 occurs at any one time only between adjacent points of intersection 22.

The complete width 11 of strip 10 consists of the I length of a leg from the large E plus the length of a leg from the small E plus four times the width of the base of back portion of an E (this being that portion bordering t created near points 22 during stamping, and as disclosed in the Small patent a generally circular aperture 22a is punched, which encompasses the points 22. The shape of aperture 22a may vary but a small circular aperture is preferred. The diameter of such aperture is not critical and should be large enough to prevent the formation of spurs. In practice, apertures 220 are too small to be used for piloting. For example, in an endless strip of metal having a width of 1 inch, an aperture having a 1/16 inch diameter is ample. There is no particular relation between aperture diameter and strip width and it is not necessary to change the aperture diameter to match any strip width. It is apparent, however, that the spacing between adjacent apertures 22 along strip 10 mayvary with strip width due to geometrical considerations.

Apertures 22 may ordinarily be too small to function as pilot apertures for feeding strip 10 through a press. However, it is possible to enlarge apertures 22 sufficiently for pilot purposes. In such case, depending upon strip width, the metal punched out will be scrap and the percentage of scrap may rise to a small but appreciable value. Adjacent Es along the outer rows are stamped simultaneously from rows 16 and 17 and are removed from strip 11 at lines 23a and 23b.

The skeleton now becomes a reduced center strip .composed of rows 14 and 15. The strip width is now the length of legs of both small and large E's plus the base of both small and large Es line 25 and 26.

Removing adjacent Es l6 and 17 simultaneously from outer edges of strip ,1 l removes any camber which may have existed in initial strip 11 before or after removal of 180 notches 22b and 360 hole 1/16 diametcr 22a on imaginary line 12. 22b 180 aperture and 22a 360 hole are stamped prior to removal of small and large Es from rows 16 and 17. These holes are not used for piloting purpose and are solely for removal of any spurs thatmay be created by subsequent E stamping or cut off.

The general stamping or punching procedure is disclosed in FIG. 4 which differs from the Schwennesen Pat. No. 3,456,535. As illustrated in FIG. 4, six stations for operating the metal strip are illustrated. It is understood that in a progressive die, the metal will be fed intermittently through successive stations. 1

Station one is where aperture 22a is punched along imaginary line 12 of strip 10. Station 2 is where l notches are punched on lines 18 and 19 of strip 10. it is understood that once aperture 22a has been punched, it is automatically and accurately fed to take up position in station 2 and subsequent stations.

Station 3 is where large and small Es 16a and 17a are punched from outer edges of strip 10 bisecting the 22b holes to at line 23a and 23b and dischargedthrough die aperture.

Station 4, small E 14a is removed from row 14, pilots 25 and 26 engage in slot created by stamping in row 15. At this station hole 22a is mutilated, 90 of hole 22a becoming part of small E 14a. This stamping occurs on line 12 and 21a.

Station 5 is idle.

Station 6, remaining strip which is now the width of the leg and base of one large E is cut off bisecting remaining of 22a hole at line 2117 on row 15.

The construction of the die is that each of the four E laminations, two large Es and two small Es are discharged through the die and will emerge as continuous stacks with 90 of the hole 22a and 90 of the two notches 22b evident on all outside corners of the bases of both large and small Es.

What is claimed is:

- 1. In the art of making transformer laminations from a continuous strip of magnetizable material, wherein a complete lamination layer consists of large and small opposed complementary E's, each E having a base and legs extending laterally from the front edge of the base, each outer leg having a width equal to half the width of the center leg and being equally spaced therefrom, the legs of a large E being equal in length, the legs of a mating small E being equal in length, the bases of both E's being equal in width and length, a pair of complementary Es in a lamination layer being disposed with their legs extending toward each other in abutting relation and the bases being paralleled with the rear of each base being on the outside of onelamination layer; said continuous strip of material having its width equal to two component widths, one component width being equal to twice the widthof the base of one E plus the length of the leg thereof, the other component width being equal to twice the width of the'base of the other complementary E plus the length of the leg thereof, the width of such strip being constant and an imaginary dividing line between such component widths being straight and extending longitudinally of the continuous strip parallel to the strip edges; there being on one side of such dividing line said one component strip portion accommodating a pattern havingtwo rows of interlocked equal E's, the rows extending longitudinally of the strip and the Es of the outer row having their bases extending continuously along the strip edge and imaginary lines extending transversely of the two outer rows of the continuous strip at regular intervals corresponding to the length of an E and a right angles to the strip edges, and the bases of the Es in the inner row extending continuously along the dividing line and all the legs extending transversely of the strip; said other component strip portion accommodating a pattern having two rows of complementary equal Es arranged in'the same manner as in the one component strip portion, the E pattern being such that the legs of the Es in the two outer rows extending along the outer edges of the entire magnetizable material strip extend toward each other in transverse alignment; the inner rows of Es having their legs aligned but extending away from each other, the method which includes the following steps,

a. stamping small generally circular apertures in the metal strip along the imaginary dividing line at regular intervals corresponding to the length of an E! b. stamping small generally semi-circular apertures in the metal strip along the outer edges of the two outer rows at each of said transversely extending imaginary lines, the base of each said generally semi-circular apertures being coincident with the outer edge of the strip.

c. stamping, from one large outer E row and one small outer E row on said strip, one large B and one small E, originally in transverse alignment on said strip with the transverse ends of said stamped E's terminating at said small apertures to leave Es in the remaining two inner rows attached to each other in succession, along each of said remaining two rows,

d. piloting the strip metal through successive stamping stations by pilot members extending through the strip metal at regions where metal has-been removed,

e. shearing E from the remaining inner row along said transverse imaginary lines,

f. controlling the dischargeand stacking of stamped Es so that a small E and complementary large E, originally transversely aligned in the original strip are paired to make a lamination layer. 

1. In the art of making transformer laminations from a continuous strip of magnetizable material, wherein a complete lamination layer consists of large and small opposed complementary E''s, each E having a base and legs extending laterally from the front edge of the base, each outer leg having a width equal to half the width of the center leg and being equally spaced therefrom, the legs of a large E being equal in length, the legs of a mating small E being equal in length, the bases of both E''s being equal in width and length, a pair of complementary E''s in a lamination layer being disposed with their legs extending toward each other in abutting relation and the bases being paralleled with the rear of each base being on the outside of one lamination layer; said continuous strip of material having its width equal to two component widths, one component width being equal to twice the width of the base of one E plus the length of the leg thereof, the other component width being equal to twice the width of the base of the other complementary E plus the length of the leg thereof, the width of such strip being constant and an imaginary dividing line between such component widths being straight and extending longitudinally of the continuous strip parallel to the strip edges; there being on one side of such dividing line said one component strip portion accommodating a pattern having two rows of interlocked equal E''s, the rows extending longitudinally of the strip and the E''s of the outer row having their bases extending continuously along the strip edge and imaginary lines extending transversely of the two outer rows of the continuous strip at regular intervals corresponding to the length of an E and a right angles to the strip edges, and the bases of the E''s in the inner row extending continuously along the dividing line and all the legs extending transversely of the strip; said other component strip portion accommodating a pattern having tWo rows of complementary equal E''s arranged in the same manner as in the one component strip portion, the E pattern being such that the legs of the E''s in the two outer rows extending along the outer edges of the entire magnetizable material strip extend toward each other in transverse alignment; the inner rows of E''s having their legs aligned but extending away from each other, the method which includes the following steps, a. stamping small generally circular apertures in the metal strip along the imaginary dividing line at regular intervals corresponding to the length of an E, b. stamping small generally semi-circular apertures in the metal strip along the outer edges of the two outer rows at each of said transversely extending imaginary lines, the base of each said generally semi-circular apertures being coincident with the outer edge of the strip. c. stamping, from one large outer E row and one small outer E row on said strip, one large E and one small E, originally in transverse alignment on said strip with the transverse ends of said stamped E''s terminating at said small apertures to leave E''s in the remaining two inner rows attached to each other in succession, along each of said remaining two rows, d. piloting the strip metal through successive stamping stations by pilot members extending through the strip metal at regions where metal has been removed, e. shearing E from the remaining inner row along said transverse imaginary lines, f. controlling the discharge and stacking of stamped E''s so that a small E and complementary large E, originally transversely aligned in the original strip are paired to make a lamination layer. 